The Madsen was the first successful light machine gun, entering production in 1902. It saw much use, but was an unusual design – basically a fully automatic falling block action. It used a top mounted magazine offset to the left side of the receiver, allowing the sights to remain on the centerline of the gun. The Madsen was available in a wide variety of calibers, configurations, and barrel lengths.
History and operation:
Running a semiauto Madsen LMG in a 2-gun action match:
Madsen Nomenclature (multiple languages)
Madsen 1904/1912 comparison (English)
Description of the Madsen Model 1940 (English)
Madsen belt-fed tank gun
Madsen also produced a belt-fed variant of their long-lived light machine gun for use in armored vehicles (their is a similar aircraft version as well). We found a parts kit for one of these guns and took a bunch of photos of it (click here to download the whole gallery in high resolution):